This happened to me recently, and I wanted to share with you my "boo-boo" so that you don't end up the same way.
I bought some sites, as we all do, and gave out my hosting credentials. I thought nothing of changing them immediately, and put off changing them until later. I list 2 auctions, and not even two days later, my Flippa account gets suspended!!!
They told me it was due to email spamming the site for sale!!! I assure you I didn't send the emails. Their support was awesome and very understanding.
But rest assured, anyone that doesn't protect their credentials after EVERY site transfer will suffer the same fate, sooner or later.
And for the record: My account is no longer suspended and I change my credentials EVERY time after giving them out.